1. Field of the Invention
This invention relates to electrical cables, and more specifically to high flex-life electrical cables for transmitting high bandwidth signals.
2. Background of the Invention
A tape library is an automated data storage system used to store data on magnetic tape cartridges. A tape library typically includes tape drives for reading and writing information to magnetic tape cartridges, access ports for entering and removing cartridges from the tape library, and a moving robot (i.e., an accessor) to physically transport tape cartridges between storage cells, drives, and access ports. The robotics associated with the accessor enable the accessor to move in left and right directions (X-motion) and up and down directions (Y-motion). The accessor typically includes motors and controller cards that require power and the ability to communicate with a stationary library controller.
To transmit electrical power and data signals between a stationary library controller and a moving accessor, one option is to use a cable assembly comprising flat parallel conductors, such as is used in the IBM 3494 and 3584 tape libraries. Although effective, flat parallel conductors have limited signal bandwidth and noise immunity as a result of the flat straight conductors. Thus, if bandwidth requirements continue to increase, this technology will eventually reach its limit. Another option is to use moving contacts that slide on fixed conductors like those used in the Sun-STK SL8500 tape library. This solution has various drawbacks such as contact wear, noise generation, limited bandwidth, and the limited number of signals that can be transmitted using this approach. Yet another option is to use non-contact means for transmitted power and electrical signals such as by using inductive coupling or wireless communication. Although effective to eliminate wires, this solution may require addressing issues such as electromechanical complexity, power transmission efficiency, electromagnetic compatibility (EMC), and radio frequency interference (RFI). This solution may also require isolating the communication signal from other wireless systems for security purposes or to prevent interference.
In view of the foregoing, what is needed is a flexible cable assembly to efficiently transmit electrical power and data signals between a stationary library controller and a moving tape library accessor. Ideally, such a flexible cable assembly would provide high-bandwidth signal capability and high noise immunity. The flexible cable assembly would also ideally have a very high flex life.